1. Field of the Invention
The present invention relates to a fast-releasing controlling device, and in particular to a fast-releasing controlling device of an actuator suitable for an electric sickbed.
2. Description of Prior Art
It is well known that actuators can be widely used in electric sickbeds, treadmills, and wheelchairs for adjusting or changing the positions or inclination thereof. When a patient is subjected to an emergent medical treatment, a fast-releasing controlling device capable of generating a fast-releasing action on the actuator can rapidly change and adjust the position of the sickbed, thereby to strive for the most important time for rescuing the patient. Therefore, it is an important issue for those skilled in this art to develop such fast-releasing controlling device of an actuator.
Taiwan Patent Publication No. M275836 discloses a conventional fast-releasing controlling device of an actuator. The actuator comprises a motor means and a transmission means. The motor means comprises a motor and a worm projecting outwardly from the center of the motor. The transmission means comprises a screw rod, a worm gear connected to one end of the screw rod and engaged with the worm, and a base covering one end of the screw rod and the worm gear. The fast-releasing controlling device utilizes a turning arm and a cable connected to one end of the turning arm to control the clutching action between the worm gear and the worm, thereby to achieve the fast-releasing action of the actuator
However, when in use, there are still some drawbacks existing in the conventional fast-releasing controlling device of an actuator. Since the turning arm presses onto the base with a fulcrum to swing in a curved manner, the direction of the applied forces of the turning arm and the cable change continuously. As a result, the applied force should be larger, causing the operation less smoothly. Further, the base is provided with holes for allowing the insertion of the turning arm. Thus, moist or dust often penetrates into the base, causing the corrosion of the internal components and in turn the substantial reduction in lifetime. Therefore, there is still much room for improvement.